The curing of coating systems containing activated double bonds by actinic radiation, such as UV light or electron beam radiation for example, is known and is established in industry. Actinic radiation is understood to be electromagnetic, ionising radiation, in particular electron beams, UV beams and visible light (Roche Lexikon Medizin, 4th edition; Urban & Fischer Verlag, Munich 1999). It is one of the fastest curing methods in coating technology. Coating agents based on this principle are therefore referred to as radiation-curing or actinically curing or curable systems.
Formulations in which all constituents crosslink by radical polymerisation, i.e. systems having a solids content of 100 wt. %, are an embodiment of radiation-curing coating systems. The absence of volatile constituents only slightly reduces the applied coating thickness of these systems having a solids content of 100 wt. % during the curing process. This slight shrinkage makes it more difficult to produce matt surfaces by the simple addition of conventional matting agents to the coating formulation. An alternative to producing matt surfaces with the aforementioned coating systems is for example the mechanical structuring of the uncured surfaces by means of appropriately structured rollers or by applying films having a defined structure, as disclosed for example in EP-A 1 914 215 or EP-A 0 578 957. The films having a defined structure are removed again once the coating has cured. However, such methods are difficult in terms of reproducibility and very labour-intensive.
The pretreatment of radiation-curable coating systems with high-energy radiation in a wavelength range of <230 nm to produce very matt coating surfaces is also known, as disclosed for example in Schubert et al. Farbe+Lack 117/5 (2011) p. 21 ff, Bauer et al. Progress in Org. Coatings 69 (2010) p. 287-293 and Bauer et al.